<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title></title>
	<style type="text/css">
      /*   行内样式 > id > 类选择器 > 标签		*/
      #d{
      	background: skyblue;
      }
		.box{
			background: green;
		}
		div{
			width: 200px;
			height: 200px;
			background: pink !important;
		}
	</style>
</head>
<body>
      <div style="background:blue;" id="d" class="box"></div>
</body>
</html>